/**
*
* @param head ListNode类 the head
* @return bool布尔型
*/
function isPail( head ) {
let arr = [],res = []
let cur = head
while(cur){
arr.push(cur.val)
res.push(cur.val)
cur = cur.next
}
arr.reverse()
for(let i = 0;i < arr.length;i++){
if(arr[i] != res[i]){
return false
}
}
return true
}